Stenopelix, Leptoceratops, Beg tse and Auroraceratops

Leptoceratops gracilis (Brown 1914; Latest Cretaceous; 2m long) is a late surviving member of an early radiation of bipedal ceratopsians that probably browsed while quadrupedal. The ventral maxilla was convex. The skull was narrower than most.

Auroraceratops rugosus (You et al. 2005; Aptian, Early Cretaceous; IG 2004 VD 001; skull length = 20cm) is a basal neoceratopsian known from a skull only. It nests with Stenopelix, which does not preserve a skull. The hook-like rostral is missing and so is the median crest.

Beg tse (Yu et al. 2020; Aptian, Early Cretaceous) nests with Auroraceratops in the LRT.

Stenopelix valdensis (Meyer 1857; Early Cretaceous, Barremian, 125 mya; Germany) is a small ornithischian dinosaur based on a single partial skeleton preserved in part and counterpart in dorsal view. Stenopelix has been difficult to classify for about 150 years because it lacks a skull. Various authors listed in Wikpedia have weighed in on the nesting of this enigma. Early pachycephalosaur (Maryanska and Osmólska 1974); Early ceratopian (Sues and Galton 1982); Pachycephalosauria (Sereno 2000); Marginocephalia (Butler and Sullivan 2009); Ceratopsia and a sister to Yinlong (Butler et al. 2011). When Stenopelix was added to the large reptile tree, it nested between (Yinlong + Psittacosaurus) and the ceratopsians alongside Auroraceratops.

Brown B 1914. Leptoceratops, a new genus of Ceratopsia from the Edmonton Cretaceous of Alberta. Bulletin of the AMNH 33, article 36.

Butler RJ and Sullivan RM 2009. The phylogenetic position of Stenopelix valdensis from the Lower Cretaceous of Germany and the early fossil record of Pachycephalosauria. Acta Palaeontologica Polonica 54(1): 21-34

Meyer H von 1857. Beiträge zur näheren Kenntis fossiler. Neues Jahrbuch für Mineralogie, Geologie und Paläontologie 1857: 532–543.

Sues H-D and Galton PM 1982. The systematic position of Stenopelix valdensis (Reptilia: Ornithischia) from the Wealden of north-western Germany. Palaeontographica Abteilung A 178(4-6): 183-190

You H, Li D, Ji Q, Lamanna M and Dodson P 2005. On a new genus of basal Neoceratopsian dinosaur from the Early Cretaceous of Gansu Province, China. Acta Geologica Sinica 79 (5); 593-597.

Yu C, Prieto-Marquez A, Chinzorig T, Badamkhatan Z and Norell M 2020. A neoceratopsian dinosaur from the early Cretaceous of Mongolia and the early evolution of ceratopsia. Nature Communications Biology 3:499 | https://doi.org/10.1038/s42003-020-01222-7 www.nature.com/commsbio

wiki/Auroraceratops
wiki/Stenopelix
wiki/Leptoceratops
wiki/Beg_tse